We found 9 dictionaries that define the word mad hatter:

General (4 matching dictionaries)

1. mad hatter: Longman Dictionary of Contemporary English
2. mad hatter: Wiktionary
3. mad hatter: Dictionary.com
4. Mad Hatter (Avenged Sevenfold song), Mad Hatter (DC Comics), Mad Hatter (album), Mad Hatter (bank robber), Mad Hatter (character), Mad Hatter (comics), Mad Hatter (disambiguation), Mad Hatter, Mad hatter, The Mad Hatter (album), The Mad Hatter (comics), The Mad Hatter (film), The Mad Hatter: Wikipedia, the Free Encyclopedia

Business (2 matching dictionaries)

5. Mad Hatter: Investopedia
6. Mad Hatter: Financial dictionary

Computing (1 matching dictionary)

7. Mad Hatter: Encyclopedia

Slang (1 matching dictionary)

8. mad hatter: Urban Dictionary

Tech (1 matching dictionary)

9. Mad Hatter: Glossary of Insulator Terms

Definitions from Wiktionary (mad hatter) ▸ noun:  A lunatic; a highly eccentric person. Similar: lunatic, mad person, madcap, madhead, headbanger, madperson, madman, fruitcake, crazyhead, madwoman, more... Phrases: mad as a hatter, as mad as a hatter, mad hatter syndrome, mad hatter disease, more... ▸ Words similar to mad hatter ▸ Usage examples for mad hatter ▸ Idioms related to mad hatter ▸ Wikipedia articles (New!) ▸ Words that often appear near mad hatter ▸ Rhymes of mad hatter ▸ Invented words related to mad hatter